Succinic acid is a dicarboxylic acid that can be produced by fermentation. Carboxylic acids are typically obtained from the aqueous fermentation solution as the corresponding carboxylic acid salts. Such salts typically include sodium or calcium as the cation. However, other acid co-products, such as acetic acid and formic acid, are also found as salts in the same aqueous solution, thereby increasing the expense of deriving value from the fermentation process.